Didymus (Greek: Δίδυμος) is the Greek word for twin. Thomas is derived from the Aramaic word for twin. In an ancient Syriac version and in the Gospel of Thomas (80:11-12) his given name, Judas, is supplied.

The often heard phrase “My Lord and my God” that appears in

Thomas answered and said to him, “My Lord and my God!” (John 20:28)

forms a literary inclusion with the first verse of the gospel of John:

In the beginning was the Word, and the Word was with God, and the Word was God. (John 1:1)

This verse

Jesus said to him, “Have you come to believe because you have seen me?r Blessed are those who have not seen and have believed.” (John 20:29)